[coreboot] PC Engines APU2: ASM1061 and mPCIe 2 slot

[Kamil Wcislo]

Hi all,
We've been investigating lately the issue with ASM1061 on the APU2 board,
because it often turns up in different discussions. Problem is, that the mPCIe 2
slot on APU2 platform is not working the same as mPCIe 1 slot. Controller is not
detected, and even if it is, the machine enters boot loop (after some disk is
physically connected).I've pinpointed the location of the machine reset to AHCI
port detect routines in SeaBIOS. I've made some notes about my investigation
here: https://github.com/pcengines/apu2-documentation/blob/master/docs/debug/mpcie2.md

WLAN cards, as far as I know, work without major problems. The one difference
between the slots is that mPCIe 2 is actually using PCI express channel
dedicated to graphic card (so is using the root complex in north bridge),
whereas mPCIe 1 is using PCI express root complex from the south bridge.

Does anybody have any insights, where could I look further to investigate this
issue, because I'm stuck at the moment?

-- 
Best regards,
Kamil Wcisło
Embedded Systems Engineer
http://3mdeb.com | @3mdeb_com